The adage that we learn more from our failures than our successes holds true for many endeavors – from classes we take in school to entrepreneurial efforts we might undertake later on in life. The mistakes and failures teach us invaluable lessons which, in the case of a new product introduction, can make that product more reliable, easier to use, more efficient, or better in many ways.
The basic construction of my seasonal storage system began by excavating a big hole in the ground. Then foam board and 12” of spray foam proivdes the insulation. Next add a pond liner, fill it with sand and heat exchangers, then half fill that with water. Foam it in and bury it under a foot of earth. We used sand as the basic fill in order to have structural stability. If it was just a water tank we would not be able to drive or build over it. Here is a link to the description and pictures of the storage tank for more details: Seasonal Storage.
The problem I have been working on recently is to figure out how ground water might be getting into the tank (see “Backup Systems Required” for more information) and, more importantly, how we might fix it without excavating the whole thing. With help from a friend (thanks Karl!) we dug 4 holes around the tank to about 3 or 4’. We found water in two of those holes at less than 2’ from the surface. So it is very likely that the water is finding its way through cracks in its insulation and then through the overlap of liner material, which is probably only 4-5′ feet from the surface.
If we can divert that water away from the tank, that could be enough to keep new (cold) water from flowing through. We want the water in the tank to be a closed system – no water enters or leaves. The water that is in there is pumped through a heat exchanger whenever the sun is out which will continue to heat it up. Last summer the tank temperature rose to over 175F. Then, in the winter, the house will use some of that stored heat and each sunny day will provide some heat back into the tank.
The next step was to come up with a good way to divert the water away from the tank. The right way to do this will be with a curtain wall or french drain type of system. But since it is winter and quite a bit of the ground is frozen we thought we would look into an active sump pump in a single deep hole to get us through until spring. With some friends at Wanner Earthmoving (thanks Bill and Gale!), we excavated a 7-8’ hole near the tank where we installed the temporary sump pump. It has only been 2 weeks since we did that and not much sun, but so far the water level inside the tank is holding steady. I’ve seen the tank temperature go from 90F to 100F on a good sunny day… so I’m very hopeful!